KVM: arm64: Improve out-of-order sysreg table diagnostics

Adding new entries to our system register tables is a painful exercise,
as we require them to be ordered by Op0,Op1,CRn,CRm,Op2.

If an entry is misordered, we output an error that indicates the
pointer to the entry and the number *of the last valid one*.

That's not very helpful, and would be much better if we printed the
number of the *offending* entry as well as its name (which is present
in the vast majority of the cases).

This makes debugging new additions to the tables much easier.

Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20240410152503.3593890-1-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index c9f4f387155f..33efa441e21d 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -3069,12 +3069,14 @@ static bool check_sysreg_table(const struct sys_reg_desc *table, unsigned int n,
 
 	for (i = 0; i < n; i++) {
 		if (!is_32 && table[i].reg && !table[i].reset) {
-			kvm_err("sys_reg table %pS entry %d lacks reset\n", &table[i], i);
+			kvm_err("sys_reg table %pS entry %d (%s) lacks reset\n",
+				&table[i], i, table[i].name);
 			return false;
 		}
 
 		if (i && cmp_sys_reg(&table[i-1], &table[i]) >= 0) {
-			kvm_err("sys_reg table %pS entry %d out of order\n", &table[i - 1], i - 1);
+			kvm_err("sys_reg table %pS entry %d (%s -> %s) out of order\n",
+				&table[i], i, table[i - 1].name, table[i].name);
 			return false;
 		}
 	}